VoIP is a way to use the public internet to make local and long distance telephone calls. It works off your existing internet service.

VoIP stands for 'voice over IP' - where 'IP' means 'internet protocol', a technology that drives the internet.

'Normal' telephone calls are made thru the public switched telephone network (PSTN). International PSTNs are interconnected to create a worldwide network specifically designed for voice communications.

Billions have been invested in building PSTNs and they perform exceptionally well. At the same time, PSTNs have well established economics supported, in part, by history and government regulation.

VoIP networks and services operate differently. VoIP has very different economics driven by how the internet works as compared to how PSTNs work. The result is that VoIP providers can deliver calls at much lower prices.

At the same time though, VoIP services are different in another important way: call quality is (or can be) lower. That's because internet technology is designed for websites and email, not voice calls. More on call quality.

1. VoIP-to-VoIP Call

This involves a VoIP caller connecting directly to another VoIP caller. Usually the call needs to be with someone on the same VoIP network since most VoIP networks don't 'talk' with other VoIP networks. Because such calls are simply another use of your existing internet connection, VoIP-to-VoIP calls are generally free (at least within the same VoIP network).

2. VoIP-to-Telephone Call

This is when a VoIP caller dials 'out' of the VoIP network to a regular telephone on the PSTN. Since such calls utilize, at least in part, the PSTN (public switched telephone network), they are generally not free.

Charges for such calls vary based on a number of factors, including where the origination and termination points are. Generally though, VoIP-to-telephone calls are cheaper than regular telephone-to-telephone calls because they use the internet at least partly.

3. Telephone-to-VoIP Call

This is when a person using a regular phone dials 'in' to a VoIP caller. Like VoIP-to-telephone calls, these calls are also not free. Applicable charges will vary, but will usually be markedly lower than a telephone-to-telephone call.

A major factor in determining the call cost is the type of phone number the telephone caller dials. For instance, are they dialing an overseas phone number subject to long distance rates or a local phone number that is free (or nearly free) to the caller?

For a fee, many VoIP providers can assign you an in-country local phone number. Using that number, your friends and colleagues can call you as if you were around the corner. Unfortunately, such services are not offered in United States right now, but may be in the future.

1. Calling Card VoIP

This type of VoIP service works like a calling card. You buy minutes, either as an actual calling card or as a monthly subscriber. Then from a regular phone, you dial a special access number, enter a PIN, and then dial your destination telephone number. This approach uses VoIP for the 'long haul' part of the call, but the regular phone network at either end.

2. Web-activated VoIP

With this type of VoIP service, you go online and initiate a call by entering the originating and destination telephone numbers. The VoIP provider then automatically dials each party separately and each phone rings at the same time. When you each answer, the call is completed. Like calling card VoIP, this approach uses VoIP for the 'long haul' part of the call and then the local phone networks at each end.

3. Telephone-based VoIP

Telephone-based VoIP services involve subscribing to a service - and buying the right gear - to allow you to make VoIP calls from your regular telephone - or from a special VoIP phone that looks like a regular telephone. In terms of the gear, you need to buy at least a VoIP phone adapter that connects your phone to your modem or router and then, in turn, to your internet connection. Depending on the specific service, you may be able to use your regular telephone or you may have to buy a special VoIP phone. In many cases, you can set up such systems to support 'dual mode' calling - meaning you can choose whether to make a call using your VoIP provider or using your regular telephone company.

4. Computer-based VoIP

This type of VoIP service is maybe the most common - you use a headset (or USB wireless handset) from your computer to 'dial' other people thru your VoIP provider. It requires you to download a VoIP software application that doubles as an address book - and you need a USB headset or the like. lf you talk to another person on a VoIP connection, then you've used the VoIP network for the entire call. If the receiving party is on a regular landline or mobile phone, then that part of the call is handled on the regular telephone network, not the VoIP network.

Because VoIP calls are made thru the public internet, you may find that VoIP call quality is lower than for regular phone calls. Like cell phone reception, actual VoIP call quality may vary from call to call.

For many purposes, any loss of call quality is made up for by lower costs and convenience. But if you are making calls for business or other reasons where you need flawless connections, you may want to look elsewhere.

It's worth noting that VoIP call quality is improving day-by-day as VoIP technologies improve and internet capacity increases. VoIP call quality today is dramatically better than even a couple of years ago - and quality will continue to improve in the coming years.

Although many of the quality problems are out of your control, you can do a few things to improve your call quality:

Use a broadband internet connection

Use high quality VoIP phone gear

Ensure that your VoIP equipment is properly connected and configured

Test your VoIP equipment and adjust settings as necessary

Getting these things right will reduce, and maybe even eliminate, call quality problems.

To make some kinds of VoIP calls, you not only need a VoIP service provider, but you also need some VoIP phone gear as well. What you need depends on the kind of VoIP service you have - see the above section Types of VoIP Service and the Use VoIP page for details on the 4 types of VoIP service providers (note: only the second two require any extra equipment).

Here's a review of the main types of VoIP phones and accessories.

1. USB VoIP Headsets

To use a VoIP service thru your computer, you need a phone headset that connects either to a USB port or to your microphone and speakers jacks. There are many options to choose from: over-the-head, behind-the-head, ear-buds, folding ones, etc., etc. Prices vary, but a decent headset costs $25 or less.

2. USB VoIP Phones

If you want a more phone-like experience while using VoIP on your computer, you can buy a USB VoIP phone. A USB VoIP phone connects to your computer with a USB cable and works similar to a regular phone. There are also wireless USB VoIP phones that allow you to move around while talking.

3. VoIP phone adapters

VoIP phone adapters are used to connect your regular telephone to your broadband internet connection. These devices attach in one direction to your regular telephone with a normal phone line and in the other direction to your internet modem or router. Once connected, you can make and receive VoIP calls using your regular phone.

4. VoIP phone systems

A VoIP phone system combines a VoIP phone with a VoIP phone adapter. The adapter connects the VoIP phone handset to the internet via your modem (or router). The connection bypasses your computer, so you can make internet calls whether your computer is on or off - it doesn't matter. Some VoIP phone systems are 'dual mode' meaning that they work both with your VoIP service and with your regular telephone carrier. You select the mode for each call you make.

Note: Before you buy any VoIP phone gear, make sure it is compatible with your VoIP provider. Equipment is often not interchangeable between VoIP providers because of differences in technologies and protocols. Of course, this does not apply to USB headsets which are generic and will work on your computer with any VoIP service.